The New Mind Readers

The New Mind Readers: What Neuroimaging Can and Cannot Reveal About Our Thoughts

Mind reading is usually thought of as a magician’s party trick. Yet advances in brain imaging have revived interest in this seemingly fictional feat. Can neuroimaging be used in court to show that a person is telling the truth or is in pain? What can neuroimaging tell us about what people think or how a specific person will behave?

In his book The New Mind Readers, Russell Poldrack addresses these and other tantalizing questions, presenting a clear and engaging overview of what neuroimaging can and cannot tell us about a person’s thoughts, perceptions, and intentions. Going beyond basic mechanisms, Poldrack tackles a number of fundamental questions about the research process, data interpretation, and applications for everyday life.

Throughout the book, Poldrack presents the vast possibilities of neuroimaging while clearly articulating its limitations. Although it is possible, for example, to decode activity in the visual cortex in order to identify the general features of an image being viewed by an individual in a functional magnetic resonance imaging scanner, it is not possible to extrapolate an underlying emotion or mental state from brain activity if an individual is not performing a task specifically designed to elicit that emotion. Deducing a person’s mental or emotional state solely on the basis of brain activity, a process called reverse inference, remains an important challenge that will require a more detailed understanding of how complex emotions are processed and represented throughout the brain and how brain activity gets combined across time and space.

A fascinating set of issues emerge when we attempt to extrapolate research results to a single individual. Neuroimaging adds an additional layer of complexity: Each person’s brain is a bit different, and brain activity can change over time. Poldrack outlines these limitations as he explores the implications of using neuroimaging data in a variety of settings, including the justice system, economic analyses, and marketing.

The reciprocal relationship between advances in neuroimaging and those in other fields is well illustrated in questions of addiction and mental illness. Addiction, as we now understand it, is both a disease that can be understood by imaging brain reward pathways and a highly context-dependent illness, indicating that activation of these pathways can be repressed. Similarly, although we now conceive of mental illness as a brain disease—a realization that has revolutionized our approach to mental illness—this has led some to wonder whether interventions can ever hope to override an individual’s biology.

In the end, Poldrack is optimistic that the development of more specific imaging approaches should eventually enable at least a basic “dictionary” linking specific brain activity patterns to certain thoughts, activities, or emotions. Such insights, however, will likely be akin to the rudimentary comprehension of a newly arrived person in a foreign land, offering only a glimpse at a complex mental landscape.